The present invention pertains to optical translators and particularly to Gray to binary code optical converters. More particularly, the invention pertains to very high speed Gray to binary code optical converters for translation of signals from a first Gray code to a second binary code and vice versa.
Binary code representation of information signals is well known in the art. Two widely used codes are the conventional binary code and the reflected binary code which is also referred to as Gray code. Both the binary and Gray codes are often translated to the other for advantageous reasons in signal processing. Gray code is greatly favored because a single bit reversal (i.e., a bit error does not result in a large quantitative error).
The conversion of signals from the Gray (G) code to binary (B) code may be expressed as EQU B.sub.0 =G.sub.0 EQU and EQU B.sub.n =G.sub.n .sym.B.sub.n-1 for n.gtoreq.1, EQU G.sub.n =B.sub.n .sym.B.sub.u-1 for n.gtoreq.1
where ".sym." is an exclusive-OR function, "0" is the most significant bit, and as n increases the bit becomes less significant.
FIG. 1 is a truth table showing decimal numbers and corresponding four bit Gray and binary codes. Various approaches have been developed for translating signals from one code to another. One approach has been to use digital logic techniques including the exclusive-OR logic function to implement the translations. Various other cumbersome techniques, including quasi-optical circuitry, incorporating the exclusive-OR function, have been used for translating from one code to the other. None resembles the present invention.